Testosterone Ups Blood Clot Risk by 63% In First 6 Months

Men who start testosterone therapy are 63% more likely to have a Venous Thromboembolism (VTE) in the first 6 months of treatment, with the risk peaking at 3 months. Over 6,300 lawsuits have been filed by men who were injured by blood clots, heart attacks, and strokes.

Venous Thromboembolism (VTE) is a blood clot the veins that breaks off and and travels in the bloodstream until it gets trapped in the lungs. It actually refers to a combination of two life-threatening conditions — Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE).

The study found a 63% higher risk of VTE — but only during the first 6 months of treatment. That translates to an additional 10 cases of VTE for every 10,000 men who start testosterone.

“The risk peaks rapidly in the first three months and declines gradually,” explained lead study author Dr. Carlos Martinez.

In 2013, a study found a 30% increased risk of stroke, heart attack, and death in the first 90 days of treatment with testosterone. In January 2014, another study found that men over 65 were twice as likely to have a heart attack in the first 90 days of testosterone therapy.

While some studies have found no risk of blood clots from testosterone overall, Dr. Martinez said these studies were flawed because they did not focus on the first 3-6 months. He recommended:

Patients should be informed of the symptoms and signs of deep vein thrombosis [DVT] and pulmonary embolism [PE] — for example, leg pain, leg swelling, or shortness of breath, and be told that, if such symptoms occur, they should bring these to the attention of a doctor.”

The study was published on November 30 in the British Medical Journal. The conclusions were based on data from 2.22 million men in the United Kingdom, including nearly 20,000 men who had a VTE between 2001 and 2013.

The FDA already requires warnings about venous blood clots on the label for testosterone products. The agency is also investigating the risk of heart attack, stroke, and death. Concerns about side effects have grown in recent years as prescriptions have skyrocketed.